1. Field of the Invention
The present invention relates to a PWM power module system and a method for operating the same, and more particularly to an interleaved-PWM power module system and a method for operating the same that is implemented by performing a phase-locking operation.
2. Description of Prior Art
In order to meet the development tendency of electronic products, that is, features of the produces tends to high power, high speed, and small size, the power densities of the electronic products increase as a result of their smaller volume. Also, the electromagnetic interference (EMI) noise is generated from the electronic components due to layout of the electronic components in a small layout area. The EMI disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit, but have become more of problems as design of electronic apparatuses.
EMI is unwanted effects in the electrical system due to electromagnetic radiation and electromagnetic conduction. Electromagnetic radiation and electromagnetic conduction are differentiated by the way an EM field propagates. The two main types of EMI are conducted and radiated. Conducted EMI is caused by the physical contact of the conductors as opposed to radiated EMI which is caused by induction without physical contact of the conductors. For example, conducted EMI is passed over wires and cables from a source or emitting to the receiver, and more particularly, the conducted EMI could be interfered mutually between wires in an electrical apparatus. The most common solution to radiated EMI is electromagnetic shielding and grounding. Accordingly, an EMI filter is installed between the AC source and the electronic circuits to restrain the EMI. The EMI filters can be provide to efficiently restrain the circuit noise, and to increase anti-interference capability and system reliability for the electronic apparatuses. Hence, the EMI filters are widely applied to electronic measurement instruments, computer room facilities, switching power apparatuses, control and measurement system, and so on.
The prior art PWM power controller was provided with an EMI filter for each of the power modules in order to reduce input ripple current and output ripple current. However, the provision of the EMI filters increases costs and it is difficult to expand the power modules.
U.S. Pat. No. 5,861,734 disclosed a control system for interleaved converters. The converter circuit includes two interleaved boost circuits, and the control system uses a single PWM controller, which operates at a fixed switching frequency with two 180 degree out-of-phase outputs, to control the switches in both of the interleaved boost circuits. The control system is mainly formed by a PWM controller, a current amplifier and filtering circuit, and a voltage feedback control circuit. A current signal is produced by the current amplifier and a filtering circuit, and a feedback voltage is generated by the voltage feedback control circuit. More particularly, switches of the two interleaved boost circuits are controlled by the PWM controller according to the current signal and the feedback voltage. By regulating the boost converter switches, the single PWM controller is able to ensure synchronization and current sharing while tightly regulating the output voltage and improving the input power factor of the converter circuit.
However, the prior art converter circuit needs to be controlled by multiple interleaved boost circuits to increase switching losses of the power semiconductor devices and increase capacitor components of the EMI filters. In addition, the interleaved boost circuits are not able to provide normal operation of synchronization and current sharing as long as only one of the interleaved boost circuits is faulted.
Hence, an interleaved-PWM power module system and a method for operating the same are disclosed to provide a phase offset calculation according to the connection and sequence of a master power module and slave power modules to provide a robust full-interleaved control and flexibly expandability to reduce switching losses of the power semiconductor devices and decrease input capacitors and the output capacitors of the EMI filters to reduce costs.